Expressionmate
2004-12-18 by djbrow54
The PSIM program for the Expressionmate increments at about 13 mV. Since each bit is 10.66/4095 or 2.6 mV, this is a value of 5. This never made sense to me so I decided to do some digging. The Expressionmate outputs 14 bits of pitchbend data. I divide this by 4 to convert to 12 bits for the PSIM. This would mean that the Expressionmate is stepping by 4*5 or 20 out of 16,384. This just didn't make sense. I finally was able to look at the midi data coming from the Expressionmate. Most increments are ~15 (hex). There are a few 16 (hex) and 1C (hex) and 1D (hex). I'm not sure why the values are so different. Perhaps it is due to the width of the pressure point on the ribbon. 15 (hex) = 21. When divided by 4 and multiplied by 2.6 mV equals the 13 mV I am seeing on the outputs. Thus the Expressionmate is stepping at about 1/6 semitone. I generally attenuate this down since I don't need the full 10 volt swing so my steps are much smaller. Weird. Dave